The health aspect of the question would get a better response in the Health.SE site.
Is it a good idea for a workout? Pretty much every single "energy supplement" uses pure sugar as its base. They also typically include caffeine, b-vitamins, and other things, but the main active ingredient is the sugar. So it is widely used. Powerlifters will eat pure-sugar candy like gummy bears when they need explosive power for their heaviest lifts. Endurance athletes will use gels, or pure-sugar candy to sustain energy through their longest workouts.
However, I would suggest not becoming reliant a supplement to get you through a workout. It sort of defeats the purpose of training (in my eyes. Other opinions may differ). You also shouldn't really need a supplement to get you through every workout. Becoming reliant is usually a sign of another problem like:
- You need more cardiovascular conditioning.
- You need more sleep.
- You need to re-adjust your diet
- You are doing too much. You need to scale back and build up.
Though for those occasional workouts where you just need the energy. You're about to attempt a new PR, you had a long day at work, the neighbor's dog kept waking you up all night, etc. Then pop a few jellybeans and get through it.